1. Field
Aspects of embodiments of the present invention relate to a pixel and an organic light emitting display including the same.
2. Description of Related Art
Recently, various flat panel displays (FPDs) having reduced weight and volume as compared to cathode ray tubes (CRTs) have been developed. The FPDs include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light emitting displays.
Among the FPDs, the organic light emitting displays display images using organic light emitting diodes (OLEDs) that generate light by re-combination of electrons and holes. The organic light emitting display has high response speed and is driven with low power consumption.
FIG. 1 is a circuit diagram illustrating a pixel of a conventional organic light emitting display.
Referring to FIG. 1, a pixel 4 of the conventional organic light emitting display includes an organic light emitting diode OLED and a pixel circuit 2 coupled to a data line Dm and a scan line Sn to control the OLED. An anode electrode of the OLED is coupled to the pixel circuit 2 and a cathode electrode of the OLED is coupled to a second power source ELVSS. The OLED emits light with a brightness corresponding to a current supplied from the pixel circuit 2.
The pixel circuit 2 controls the amount of current supplied to the OLED in accordance with a data signal supplied to the data line Dm when a scan signal is supplied to the scan line Sn. Therefore, the pixel circuit 2 includes a driving transistor MD coupled between a first power source ELVDD and the OLED, a switching transistor MS coupled between a gate electrode of the driving transistor MD and the data line Dm, and a storage capacitor Cst coupled between the gate electrode of the driving transistor MD and a source electrode of the driving transistor MD.
The switching transistor MS is coupled between the data line Dm and one electrode (terminal) of the storage capacitor Cst. A gate electrode of the switching transistor MS is coupled to the scan line Sn. The switching transistor MS is turned on when the scan signal (for example, at a low level) is supplied from the scan line Sn to supply the data signal supplied from the data line Dm to the storage capacitor Cst. At this time, a voltage corresponding to the data signal is charged in the storage capacitor Cst.
The driving transistor MD is coupled between the first power source ELVDD and the OLED. The gate electrode of the driving transistor MD is coupled to one electrode of the storage capacitor Cst. The driving transistor MD controls the driving current that flows from the first power source ELVDD to the second power source ELVSS via the OLED in accordance with the voltage value stored in the storage capacitor Cst. The OLED generates light with the brightness corresponding to a magnitude of the driving current.
The above-described conventional pixel may not display an image with desired brightness due to an efficiency change caused by deterioration of the OLED. As the OLED deteriorates, light with low brightness is generated.